/*
 *  Copyright (c) 2026 Kaiy Ragur
 *
 *  This Source Code Form is subject to the terms of the Mozilla Public
 *  License, v. 2.0. If a copy of the MPL was not distributed with this
 *  file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
package notify

import (
	"log"
	"sync"
)

type EventType int

const (
	EventMailNew EventType = iota
	EventMailUpdate
	EventMailPurge
	EventFlagsUpdate
	EventHeartbit
	// ...
)
const AllUsers = "*"

type Event interface {
	GetType() EventType
	GetAccountPK() string
}
type HeartbitEvent struct {
	Type      EventType
	AccountPK string
}

func (e *HeartbitEvent) GetAccountPK() string { return e.AccountPK }
func (e *HeartbitEvent) GetType() EventType   { return EventHeartbit }

type EmailEvent struct {
	Type               EventType
	MessageId, Count   int64
	AccountPK, MailBox string
	done               chan struct{}
}

func NewEmailEvent(pk, mailbox string, id, count int64) *EmailEvent {
	return &EmailEvent{
		AccountPK: pk,
		MailBox:   mailbox,
		MessageId: id,
		Count:     count,
		done:      make(chan struct{}),
	}
}

func (e *EmailEvent) GetAccountPK() string { return e.AccountPK }
func (e *EmailEvent) GetType() EventType   { return e.Type }

// imap/backend/update interface

func (e *EmailEvent) Username() string    { return e.AccountPK }
func (e *EmailEvent) Mailbox() string     { return e.MailBox }
func (e *EmailEvent) Done() chan struct{} { return e.done }

type FlagsEvent struct {
	AccountPK string
	Mailbox   string
	MessageID int64
	Seen      bool
	Answered  bool
	Flagged   bool
	Deleted   bool
}

func (e *FlagsEvent) GetAccountPK() string { return e.AccountPK }
func (e *FlagsEvent) GetType() EventType   { return EventFlagsUpdate }

type Notify struct {
	log *log.Logger

	mu        sync.Mutex
	listeners map[string]map[chan Event]struct{}
}

func NewNotifyBus(log *log.Logger) *Notify {
	return &Notify{
		log: log,
	}
}

// Subscribe for any methods
func (n *Notify) Subscribe(pk string) chan Event {
	n.mu.Lock()
	defer n.mu.Unlock()

	if n.listeners == nil {
		n.listeners = make(map[string]map[chan Event]struct{})
	}
	if n.listeners[pk] == nil {
		n.listeners[pk] = make(map[chan Event]struct{})
	}

	ch := make(chan Event, 10)
	n.listeners[pk][ch] = struct{}{}
	return ch
}

func (n *Notify) Unsubscribe(pk string, ch chan Event) {
	n.mu.Lock()
	defer n.mu.Unlock()

	if subs, ok := n.listeners[pk]; ok {
		delete(subs, ch)
		if len(subs) == 0 {
			delete(n.listeners, pk)
		}
	}
}

// Do Notification for clients
func (n *Notify) NotifyNew(pk string, event Event) error {
	n.mu.Lock()
	defer n.mu.Unlock()
	go func() {
		if subs, ok := n.listeners[pk]; ok {
			for ch := range subs {
				ch <- event
			}
		}
		if subs, ok := n.listeners[AllUsers]; ok {
			for ch := range subs {
				ch <- event
			}
		}
	}()
	return nil
}